Pump actuators counterbalance assemblies



June 8, 1965 G. A. PRATHER PUMP ACTUATORS COUNTERBALANCE ASSEMBLIES 5 Sheets-Sheet 1 Filed May 27. 1960 .vIllIIIIIIIIIIIIIIIIIV'III INVENTOR. GEORGE A. PRATHER ATTORNEYS June 8, 1965 G. A. PRATHER PUMP ACTUATORS COUNTERBALANCE ASSEMBLIES 5 Sheets-Sheet 2 Filed y 27, 1960 INVENVTOR. GEORGE A. PRATHER %7f ATTO RNEYS M Q 7 wW Q a 3 June 8, 1965 s. A. PRATHER PUMP ACTUATORS COUNTERBALANCE ASSEMBLIES Filed May 27. 1960 5 Sheets-Sheet 3 FIGS INVENTOR.

GEORGE A. PRATHER 98 FIG9 ATTORNEYS June 8, 1965 G. A. PRATHER PUMP ACTUATORS COUNTERBALANCE ASSEMBLIES 5 Sheets-Sheet 4 Filed May 27, 1960 INVENTOR.

GEORGE A. PRATH ER June 8, 1965 e. A. PRATHER PUMP ACTUATORS COUNTERBALANCE ASSEMBLIES 5 Sheets-Sheet 5 Filed May 27, 1960 FIG. I3

INVENTOR. GEORGE A. PRATHER 'lIlIlIIIIIlII/IIIIII ATTORNEYS United States Patent The present invention is directed to improvements in lubricating and sealing systems for air balance cylinders such as are commonly found in oil well pump actuating systems.

One common form of lubricating system for such cylinders utilizes a separate pump which is actuated intermittently by the action of the walking beam with which the air balance cylinder is interconnected. The pump picks up oil from the base of the cylinder and delivers this lubrieating oil through a separate pipe to the top of the piston which works within the cylinder, thereby maintaining a pool of oil on top of the piston to insure adequate lubrication of the piston. Another form of lubricating system, such as is shown in the Delahay Patent No. 2,745,- 660 and DErrico Patent No. 2,745,704, utilizes the action of the piston rings, the pressure conditions in the cylinder, and a check valve system co-operating with the piston rings to deliver lubricating fluid through a vent passage to the top of the piston. The check valve rings of these patents are intended to open the vent passage to the passage of lubricating oil to allow flow of the lubricant to the space above the piston while preventing retrograde flow.

of oil in the cylinder space beneath the piston so that the skirt of the piston dips into.this pool of oil and carries the oil therewith for lubricating the opposed cylinder and piston walls during the relative reciprocation thereof.

The first aforementioned type of system has the disadvantages of tending to pump all of the oil from beneath the piston to the top thereof. It has the additional disadvantage that the rings in this type of system allow working of this lubricating oil from the top of the piston to and between the space between the opposed walls of the piston and cylinder. Since the system basically depends upon the lubricant working downwardly past the rings for effective lubrication of the cylinder and piston, the rings must be sufliciently loose'as to allow the lubricant to drain past the rings. When a unit of this type is shut down the oil seal which is formed at the top of the piston tends to leak out past the piston rings with the result that the seal is eventually lost along with the pressure in the counterrings changes with such conditions as the extent of wear on the'piston rings. Furthermore, if the oil drains'from the space above the piston after a shutdown, the action of the piston rings in delivering oil to the top of the piston is relatively slow with the result that valuable time is lost in building up the proper body of lubricant at the top of the piston for sealing and lubricating purposes during operation of the unit. If the pumping action of the rings is highly effective, substantially all of the oil from the base of the cylinder may be pumped to the top of the 3,187,839 Patented June 8, 1965 piston with the result that the piston is not lubricated from the bottom.

This type of system also requires considerable operator attention in observing the level of oil at the base of the cylinder, and admitting new oil if needed to insure that oil is maintained at the base of the cylinder to allow the piston skirt to dip therein for its lubricating action on the walls of the cylinder.

A major purpose of the present invention is a provision of a system which maintains balanced levels of lubricating oil above the piston and beneath the piston during operation of the air balance unit for proper lubrication of the piston from the top and the bottom, while at the same time being highly effective in quickly restoring the body of lubricating fluid on top of the piston in the event the body of fluid is lost for any reason and also assuring a highly effective seal against the loss of air from the cylinder.

Another purpose of the present invention is to provide simple and effective means for utilizing the pressure within a counterbalance cylinder for expanding the piston rings of the cylinder outwardly. for effective sealing of the piston and cylinder.

Another purpose of the present invention is the provision of improved mounting means for an air balance cylinder, which mounting means decreases the amount of head room or vertical height necessary for the use of a cylinder of a given stroke length.

Other purposes will appear from time to time in the course of the ensuing specification and claims when taken with the accompanying drawings in which:

FIGURE 1 is a side elevation of a typical pumping unit with which the present invention is associated;

FIGURE 2 is an enlarged elevation of an air balance unit of the present invention with certain portions being shown in section for purposes of clarity;

FIGURE 3 is a sectional illustration-of a portion of a. typical piston utilized in the invention;

FIGURE 4 is a top view of a piston formed in the manner illustrated in FIGURE 3;

FIGURE 5 is a sectional illustration of another piston embodying the principles of the invention;

FIGURE 6 is a plan view of a piston formed in the manner of FIGURE 5;

FIGURE 7 is a sectional illustration of another form of piston embodying the principles of the invention;

FIGURE 8 is a sectional illustration of still another form of piston embodying the principles of the present invention;

FIGURE 9 is a sectional illustration of still another form of piston embodying the principles of the present invention;

FIGURE 10 is a perspective view of a portion of the piston illustrated in FIGURE 9;

FIGURE 11 is a view of an improved supporting assembly for the counterbalance unit, with certain portions being shown in section for purposes of clarity;

FIGURE 12 is an end view of the supporting assembly illustrated in FIGURE 11; and

FIGURE 13 is a sectional view of additional elements of the lubricating system.

Like elements are designated by like characters throughout the specification and drawings.

With specific reference now to the drawings and in the first instance to FIGURE 1 the numeral 20 designates the walking beam of a typical pump actuating unit, which beam is adapted to be oscillated by the usual crank drive 21, which is driven by a motor and transmission assembly 22. An air counterbalance unit generally designated at 23 extends between the walking beam 20 and the base of the unit in such a manner that upon the down stroke of piston 37.

the beam, where the load on the unit is normally lightest,

air within the cylinder 24 is compressed whereas on the relatively heavy upstroke of the unit the air so compressed tends to help with the raising of the load. In a typical installation of this class the cylinder 24- is pivoted to the beam as at 25. while the piston rod 26 is pivoted to the base of the unit as at 27.v

The cylinder 24 is of a fwrap around design, incorporating a largeouter pressure vessel or cylinder 23 which surrounds and is spaced from an inner cylinder 29. The outer cylinder 28 and the inner cylinder 29 may have the flanged bases thereof joined together by means of suitable bolts or thelike 36. The lower portion of the outer cylinder 28 may be restricted so as to provide a relatively narrow circumferential oil receiving space 31 between the cylinder 29 and cylinder 28. An O-ring 32 may be positioned between the flanged bases of the two cylinders to assure a fluid tight seal therebetween.

The base of the inner cylinder 29 may have a plate 33 joined thereto with a tube 34 upstanding therefrom and surrounding the piston rod 2.6. The tube 34 and piston rod'26 are adequately. sealed to the base of the cylinder 29 for the retention of a body of lubricating fluid between the tube 34 and the. cylinder 29.

The upper portion of the outer cylinder 28 is defined by a metal stamping 35Vwhich is dome shaped and welded and to the inlet of the pump for delivery to the space above the piston 37. When valve 55 is closed, lubricating fluid within the cylinder 29 is prevented from passing through the pipe 54- and may passto the inlet side of the pump only when the level of lubricant within the cylinder 29 is at or above the uppermost level of the pipe 53.

The heights of the overflow pipes 53 and 54 are so proportioned that the pipe 53 is especially adapted for use with a relatively short stroke for the unit, whereas the pipe 54 has a height such that it is especially proportioned to the upper remaining cylindrical portion of the cylinder 28. VA reinforcing ring 36 may be provided atthe welded joint between the dome shaped top of the cylinder and the remaining wall of the cylinder.

A piston 37 is fixed to the upper portionof the piston,

rod 26 and has an elongated skirt 38 which is adapted to dip into thebody of lubricant at the base of the cylinder 29 during reciprocation of the piston within'the cylinder. As is conventional in this type of counterbalance unit, an under pressure is supplied through the hollow interior of the piston rod 26 to that space within the cylinder which is opposed to the compressing action of the piston. Air may be so supplied by any suitable compressor makeup assembly as are well known in the art for delivery of fluid through a conduit 39 to the holler interior, of the.

piston rod' and for delivery to the upper portion of the cylinder through a restricted tube 40 which leads through thetop of the piston.

. 41 designates a retaining bar which may be fixed to.

the top of the cylinder 29 as a convenient means in preventing movement of the piston through the top of the cylinder 29 during assembly and disassembly thereof.

In order to maintain a proper balance of lubricant at the space above the piston and the space in the lower portion of the cylinder 29, a piston type pump 42 is -mounted on a flanged bracket 43 carried by the flanged portions of'the bases of the cylinders 29 and 28. The

f pump 42 has an outlet tube 44 which leadsthrough an inlet fitting 45st an upper portion of the cylinderZd and through an outlet tube 46 which extends withinthe cylinder 28. Tube 46 is pesitionedto supply lubricating fluid within the upper portion of cylinder 29 and to the space above piston 37. The operating stem 47 for the pump extends through the flanged portion-43 of the bracket 43 and includes an enlarged lower portion 49 which is adapted to abut against a fixed portion of the pump actuating unit as is'diagrammatically indicated by the base 50. A coiled spring 51 may extend between the flange 48 and a collar 52 on the rod 49 so as to return the actuating rod to its outermost position. Upon downward movement of thecylinder assembly relative to the piston 37, the rod 49 for use with a long stroke for the unit. The heights are so selected that abody of lubricant as designated at 55a is always maintained within the cylinder 29 and at a level such that a considerable portion of the piston skirt, as for example approximately one third of the skirt or more, dips into this pool of lubricant at the upper portion of the cylinder stroke, or when the piston is. at its lowermost point of travel within the cylinder assembly.

Suitable means (not shown) may be provided for admitting oil in suflicient quantity to the lower portion of the cylinder 29.

- FIGURES 3 and 4 illustrate one form of piston assembly utilized in the invention. In FIGURE 3 the upper surface of the piston is provided with a'well-like recess 56. A plurality of piston rings 57 are mounted within a circumferentially extending groove 58 in the upper portion of the piston peripheral wall. The piston rings 57 and groove 58 are formed with a normal and conventional piston ring tolerance. A resilient sealing ring 59, which may be formed from rubber like material, is positioned will contact the base 50 at or near the lower portion of the stroke was to move the actuating rod 47 inwardly within the pump housing and cause forced elevation of lubricant through the, tube 44 and to the space above the An inlet tube 52 for the pump is in communication with overflow pipes 53 and 54 which are fixed to the base plate 33 and extend upwardly within thecylinder 29. One

between the piston rings 57 and the inner circumferential wall 69 of the groove. 58. The ring 59 has a generally U-shaped form with an inner leg 61 closely conforming to the height of the groove 58 and an outer leg 62 of shorter length. A plurality of vent passages 63 are spaced angularlyaround the top wall of the piston and communicate with the groove 53 at a point between the legs 61 and 62. p

A check value 64 is threaded into the upper portion of these passages 63 and includes a conventional ball check for allowing flow from the space above the piston to the space between thesealing ring legs and the space behind 1y past the outer walls of the piston rings 57 when pressure conditions permit (as-on the relative downstroke of the piston) to thereby elevate lubricatingfiuid to the space above the piston 37' and maintain a body of lubricating fluid above the piston as is represented at 65a in FIGURE 2. At the same time'the pressure of air within the cylinder assembly works on this pool of lubricating fluid and is transmitted through the pressure passages 63 to force the rings outwardly into tight sealing engagement with the wall of the cylinder to thereby provide a highly effective seal against the loss of air from within the cylinder.

The check valve 64, by preventing return flow through the passages 63 assures that the shape of the sealing element is maintained and is not distorted.

FIGURES 5 and 6 illustrate another form of piston construction. In FIGURES 5 and 6, the piston 65 is provided with rings-66 which are seated in a groove 67 in similar fashion to the ring and groove construction of FIGURES 3 and 4. In FIGURES 5 and 6, however, a back up ring is positioned on the inner side of the piston rings and a sealing element 69 is defined by a spirally wound resilient tube which is positioned within the groove 67 in the space between the back up ring 68 and the inner Wall of the groove. One end of the flexible tubing communicates through an inlet tube 70 with the space above the piston Where as the other end of the tubing communicates through an inlet tube 71 with the space above the piston. The inlet tubes to each end of the flexible sealing tube are sealed to the bores in the piston through which they pass as by means of threaded members 72 and 73 which compress packing elements 74 and 75 tightly against the tubing and the piston body itself.

In FIGURES 5 and 6 the normal working of the piston rings may allow the flow of oil to the space above the piston as is the case in FIGURES 3 and 4. The pressure above the piston is transmitted to the flexible tubes of this packing so as to expand the packing and thereby the piston rings tightly outwardly against the opposed wall of the cylinder during the high pressure condition of the assembly. Since the inlet fittings communicate with the interior of the tubes, lubricating fluid which may leak past the piston rings into the space in which the sealing element is located is prevented from passing through the passages 70 and 71. By formingthe sealing element in this manner the pressure above the piston is effectively transmitted to the space behind the piston rings, while retrograde flow is prevented by the action of the sealing element.

FIGURE '7 illustrates a further embodiment of the invention. In FIGURE 7 the piston 76 has rings 77 seated in a-circumfeerntial groove 78 in a manner similar to the ring and groove construction of FIGURES 3 and 4. In FIGURE 7 a packing element 79 is in the form of a hollow resilient tube of generally rectangular cross section, Which tube substantially fills the space between the piston rings and the inner circumferential wall of the 'In FIGURE 7, the pressureabove the piston is efiectively transmitted to the expandable sealing element 78 for forcing the piston rings 77 outwardly into tight engagement with the opposed wall of the cylinder under the high pressure condition of the assembly. At the same time passage of fluid through the inlet to the sealing element is eifectively prevented by the sealing action of the element against the upper wall of the groove and the tight seal between the inlet to the sealing element and the inlet bore in the piston.

In FIGURE 8 piston rings 83 are seated in a groove .84 in the piston body in a fashion similar to the ring and groove constructions afore described. In FIGURE 8, an inlet passage 85 leads to the space behind the piston rings 83 in a manner such that the pressure above the piston is directed against a generally U-shaped resilient sealing element 86 for expanding the sealing element 86 and piston rings 83 outwardly for a tight sealing engagement with the wall of the cylinder under the high pressure condition of the assembly; Several pressure passages 85 may be spaced around the top wallof the piston so as to admit the pressure above the piston to the space behind the piston rings 83. The element 86 has an inner leg 87 of a height closing conforming to the height of the groove and an outer leg 88 which is slightly shorter than the height of the groove. The connecting portion 1 89 which spans the legs of the ring has an inverted V- shaped disposition and is so molded that the apex there- 102 is passed. Pin 102 is Welded to the straps.

of designated at 90 is in close proximity to the longer leg 87 and spaced a larger distance from the shorter leg 88. Thus any pressure tending to work past the lowermost ones of the rings 83 will tend to direct the spanning portion 89 toward the leg 87 and at the same time tend to expand the leg 88 and remaining portion of the connecting span upwardly toward the inlet passage 85. This tends to cause a tight seal between the upper edge of leg 88 and the upper wall of the groove and a tight seal between the leg 87 and the inner Wall of the groove to thereby prevent flow through the pressure passages 85.

In FIGURE 8 the sealing ring 86 effectively transmits the pressure from the upper side of the piston, as transmitted through the passage or passages, 85, to the piston rings 83 for biasing the rings outwardly into tight engagement with the wall of the cylinder. At the same time the sealing ring is effective in preventing flow from the space beneath the piston, through the groove, and to the top of the piston through the passage 85.

FIGURES 9 and 10 illustrate still another embodiment of the invention. In FIGURES 9 and 10, the piston 91 is provided with rings 92 which are seated in a groove 93 in a manner similar to the seating of the rings in the other forms of the invention. In FIGURES 9 and 10 a generally U-shaped packing ring 94 is seated in the groove behind the rings 92. The ring 94 is the same as the ring of FIGURES 3 and 4. In FIGURES 9 and 10 the uppermost piston ring 95 is provided with a series of circumferentially spaced grooves 96 as is seen best in FIGURE 10. The upper portion of the piston, that is that portion above the uppermost ring 95, has a slightly smaller diameter than the body of the piston beneath the piston rings so as to provide a peripheral oil passage space 97.

Under the high pressure condition of the cylinder assembly, as for example when the piston 91 is at the upper portion 98 of the cylinder wall, oil from the pool above the piston may flow through the circumferential space 97, through the grooves 96 and past the shorter leg 99 of the packing ring so ast-o develop pressure between the legs of the packing ring and force the piston rings 92 outwardly into a tight sealing engagement with the wall of the cylinder 98. Retrograde flow of fluid is prevented by the packing ring 94.

A novel bearing assembly is provided to pivotally connect the upper portion of the cylinder to the walking beam. As is seen best in FIGURES 2, 11 and 12, the walking beam 20 has fixed to the base thereof a plate 101 to which is fixed the pivot pin 102 of the pivotal connection generally designated at 25. The plate 101 may be bolted to the lower flanges of the walking beam 20 and have depending straps 103 and 104 through which the pin The outer ends of the pin 102 are received in spaced bearing housings 105 and 106, which, as will be seen in FIGURE 2, are spaced outboard of the lower flanges of the walking beam 20 with the upper portions of the housings extending above the lower flanges of the I beam.

As will be seen in FIGURE 11, the bearing housings 105 and 106 include roller bearing assemblies 108 and 109 which receive and rotatably support the ends of pivot pin 102. The bearing housings 105 and 106 may include suitable lubricant inlets 110 and 111 and packin rings 112 and 113. Packing rings 112 and 113 surroun portions of pin 102 and elfectively'seal the housing against the loss of lubricant.

The inner walls of the bearing housing 105 and 106 are provided with laterally extended and spaced ears 114 and 115. The inner walls of the bearing housings 105 and 106 are provided with inwardly projecting shoulders 116 and 117, which shoulders are adapted to rest upon spaced plates 118 and 119 which are welded to the dome shaped top wall of the outer cylinder 28. Thus the load is transmitted directly from the bearing housings to the straps 118 and 119. The laterally extended ears 114 and .of the inner walls of the bearing housings 105 and v 8 i Q 267 and 262 and can then bleed off'lubricant to the lower sump 255. The operator can of course bleed ofi this excess lubricant through the drain 266 in the event that the I beam, thus reducing the height requirements for the as sembly. Furthermore, by so forming the bearing assembly, the load is transferred to spaced points on the upper wall of the cylinder with the result that the dome shaped upper Wall of the cylinder may be of a lighter construction than is the case' where the load is transferred directly 7 to the central portion of the cylinder upper wall.

In FIGURE13 a system is disclosed for allowing the operator of the system to periodically check the level of lubricant in the piston sump above the piston while returning a portion of this lubricant to thesump in the base of the cylinder in the event that the level in the piston sump is too high.

In FIGURE 13, the cylinder 224 and piston 237 should be taken as illustrative of the same type-of piston and cylinder assembly illustrated in FIGURE 2, with all of the elements of FIGURE 2 utilized therewith. In FIG- URE 13 an oil level gauge-24tl may be utilized to indicate the level of lubricant existing in the sump 255 in the base of the cylinder; The body of lubricant in the piston sump or above the piston is designated at 256. A conduit 257 is fixed to the wall of the outer cylinder 224 and is fixed to the cylinder 229 within which piston 237 works. i The conduit 257 includes a downwardly directed portion 258 within aninlet opening or port 259 opposed to the body of lubricant 256 in the piston sump. The lower end of the conduit 253 and port 259 is located at a level such that it is always above the uppermost position of travel of the piston within the cylinder 229. It may be located as shown in the drawings wherein when the piston is at the innermost position within the cylinder, corresponding to the high pressure condition of the cylinder, the port 259 will contact the body of lubricant 256 if the level of lubricant in this body is at a Dre-selected or desired level. If the level of lubricant is lower the port 259 will of course not contact the body but if the level is higher the port will be immersed within the body.

Conduit 257 extends through the cylinder wall and leads to a three-way valve 260. -Three-way valve 260 has a control handle 261, which upon selective movement by the operator thereof, will close conduit 257, or cause com munication of conduit 257 with a return conduit 262 or cause communication with anatmospheric outlet 263. Conduit 262 leads through a second three-way valve 26 which has a manually actuated control handle 265 for selectively closing conduit 262, allowing communication between conduit 262 and a drain port 266, or allowing communication with a conduit 267 which has an outlet within the cylinder 229 and within the sump defined in the base of the cylinder 229.

During normal operation both the valve 260 and valve. 264 are moved to the closed positions. At predetermined intervals, the operator can check the level of oil or lubricant maintained in the piston sump by moving valvev 266 to the atmospheric position after the cylinder reaches the lowermost portion ofits strokeor when the piston has moved to the innermost position within the cylinder. If the level of lubricant in 'the piston sump is higher than that desired then the pressure in the cylinder, being greater than atmospheric, will force lubricant through conduits 258 and 257 to the atmosphere. The operator by observing this exhaust will know whether or not the level of lubricant in the piston sump is higher than necessary. If the level is lower than that desired, air alone will be ex- 7 hausted through the atmospheric outlet 263. 'If oil is exhausted, indicating that the level of lubricant in this sump is too high, then the operator can move the valve 266 to the position allowing communication between conduit oil level gauge 24%? indicates that the level of lubricant in the cylinder sump is sufficiently high for working requirements.

The operator can of course, whenever the level of lubricant in the piston sump is sufliciently high, open threeway valve 264 to the drain position in the event he should desire to lower the level of lubricant in the cylinder sump Z55.

After observing the levels of lubricant in the two sumps and making any adjustments considered necessary the operation of the pump actuating unit maybe resumed. While the level is preferably checked and adjusted while the actuator is idle, it should be understood that the level in the piston sump can be checked during operation, especially in the case of slow moving actuators. Only a momentary cracking of valve 261 is necessary for the check.

In operation, a body of oil is maintained in both the lower portion of the cylinder 29 and theupper portion of the cylinder 29 above the piston 37. 'The total quantity 'of oil in these two separate bodies maybe a quantity such as to fill the cylinder 29 to a level above the higher drain pipe 53. A body of oil may also be maintained in the lower portion of the outer cylinder 23 so as to effectively seal the lower portion of this cylinder against the escape of air from the assembly. I

When the assembly is usedfor relatively short operating strokes of the pump actuating system, the valve 55 is closed so that oil is delivered by the pump 42 to the space above piston 37 only when enough oil;drains down past the piston that it may overflow into the drain pipe 53. When the system is used with relatively long strokes, the valve 55 is opened so that oil may flow into the standpipe 54 for recirculation by the pump 42 to the upper portion of piston.

During the normal operation, the piston skirt dips into 40 the body of oil that is maintained in the lower portion of the piston 29 and carries this film of oil upwardly along the cylinder wall for lubrication of the working faces of the piston and cylinder. The piston rings in all forms of theinve'ntion have normal working clearances so that they may pump small amounts of oil periodically to the upper portion of the piston. In this connection the lubricant simply works past the piston rings and along the outer periphery of the piston so as to eventually spill into the space above the piston.

With this body of lubricant maintained on the upper side of the piston the system is effectively sealed against the loss of air from the assembly under the high pressure condition of the assembly, 'as is found when the system is pressurized and with the piston at the upper portion of the cylinder. The pressure within the cylinder works on this upper body of oil and is transmitted through the passages to the spaces behindthe piston rings. The pressure is thus effectively transmitted to the piston rings in a direction such as to bias them outwardly into a tight sealing engagement with the cylinder wall.

The particular arrangement of therubber or rubber like sealing rings with the vent passages for delivering that the oil seal at the top of the piston is impaired, oil at the base of the cylinder 2%, upon accumulation,-will spill over into one or the other drain pipes 53 or 54, depending uponlt'he condition of the valve 55, so that the oil may be returned by the intermittent action of the pump 42.

If the oil seal is lost after a protracted period of shut down, theseal is quickly restored within a relatively short period of time by the combined pumping action of the rings and the pump 42.

The use of the gauging system and inspection system of FIGURE 13 is highly advantageous in that it provides a convenient means for insuring that the levels of lubricant are maintained at the, desired levels at the upper portion of the piston and beneath the piston. This is especially important where the pumping action of the rings themselves is unusually eflicient with the result that all of the lubricant tends to be moved to the space above the piston. In this event the periodic checking by the operator, through opening of valve 260 to the atmospheric position when the piston is at the innermost position in the cylinder, will allow the operator to know whether the level is proper and whether some lubricant should be returned from the piston sump to the cylinder sump.

By so maintaining and regulating the'body of oil 65 at the top of the piston while maintaining and regulating a quantity of oil at the lower portion of the cylinder 29 the piston is eifectively lubricated both from an upper direction and a lower'direction in that the oil above the piston tends to work downwardly toward the piston rings while the oil in the base of the cylinder 29 is worked upwardly by the constant dipping of the skirt 38 Within the lower body of oil.

Whereas I have shown and described several operative forms of the invention, it should be understood that this showing and description thereof is to be taken in an illustrative or diagrammatic sense only. There are many modifications to the invention which will be apparent to those skilled in the art and which will fall within the scope and spirit of the invention. The scope of the invention should be limited only by the scope of the hereinafter appended claims. 7

I claim: 7

1. The method of lubricating and sealing a pressurized cylinder and piston counterbalance assembly in which a sealing, first pool of lubricant is maintained between the pressurized cylinder space and the side of the piston opposed thereto, and in which a portion of the piston may move into a second pool of lubricant at a lower portion of the cylinder for lubrication of the opposed piston and cylinder walls, including the steps of utilizing the normal pumping action of the piston to move lubricant along said opposed walls from said second pool to said first pool, and removing lubricant from said second pool and delivering same to said first pool independently of said pumping action when the level of lubricant in said second pool increases beyond a predetermined level.

2. In a lubricating system for an air balance of the type used with pump actuators including a generally vertically extending air cylinder and a piston slidably mounted within said cylinder, means pressurizing the cylinder space against which said piston works, said piston being adapted for generally vertical reciprocation relativeto and within said cylinder, means providing a body of lubricant in the lower portion of said cylinder, said piston having a skirt adapted to periodically dip into said body of lubricant upon reciprocation of said piston, pumping means for intermittently delivering lubricant from the lower portion of said cylinder to the space above said piston when said body of lubricant in the lower portion of said cylinder exceeds a predetermined amount, said piston having at least one piston ring seated in a groove in the wall of the piston, said piston having a pressure passage extending from the upper portion thereof to said groove for delivering the pressure from the space above said piston to the space behind said piston ring to thereby bias said piston ring outwardly into a tight sealing engagement with the opposed cylinder wall, said pistgn ring having normal tolerances with said groove and cylinder wall such that said ring tends to pump oil to 10 V the top of said piston by the normal working of said piston ring within said groove during reciprocation of said piston, and means preventing flow of lubricant from the space between said piston and cylinder, through said groove and pressure passage to the space above said piston.

3. A counter-balance system for pump actuators and the like including an air counter-balance cylinder and a piston mounted for relative reciprocation in said cylinder, means for admitting air to the cylindrical space opposed to said piston, means defining a reservoir for lubricating fluid in the lower end of said cylinder, said piston having a skirt adapted to dip into the body of lubricant in said reservoir for lubrication of the opposed walls of said cylinder and piston, said piston having at least one ring engaging the wall of said cylinder and adapted to pump oil to the space above said piston through the normal working of the piston ring during reciprocation of said piston relative to said cylinder, separate pumping means for delivering lubricating fluid to the top of said piston, and means for delivering lubricating fluid from said reservoir to said pumping means when the body of lubricating fluid in said reservoir builds up beyond a predetermined level sufficient to allow said skirt to dip into said body.

' 4. The structure of claim 3 wherein said pumping means includes a conduit for delivering lubricating fluid through the upper portion of said cylinder to the space above said piston, and an actuating rod adapted for intermittent reciprocation by contact with mounting means for said actuator during relative reciprocation of said piston and said cylinder.

5. The structure of claim 3 characterized and including a resilient packing ring seated in a groove in said piston in back up relation to said rings, said packing ring being expansible against the piston rings, and means for communicating the pressure from above said piston to said packing rings so as to expand said packing rings against said piston rings.

6.- The structure of claim 3 characterized by and in cluding a resilient packing ring seated in a groove behind said piston rings, said packing ring having a flexible portion expansible outwardly against said rings, and means for communicating the pressure above said piston to said flexible portion so as to expand said rings outwardly against said cylinder wall.

7. The structure of claim 3 wherein said last-named means includes first and second drain ports in the lower end of said cylinder and positioned at different levels within said cylinders, passage means for delivering lubricating fluid from each drain port to said separate pumping means, and means for selectively establishing communication between one or the other of said drain ports.

8. A counter-balance system for pump actuators including an air counter balance cylinder and a piston mounted for relatii e reciprocation within said cylinder, means admitting air to the interior of said cylinder opposed to said piston whereby upon said reciprocation of said piston the pressure within said cylinder is increased and decreased, said cylinder having a lubricant reservoir in the bottom thereof, said piston having a skirt adapted to dip into said lubricant reservoir during reciprocation of said piston, said piston having at least one piston ring mounted in a groove therein and expansible outwardly into engagement with the opposed wall of said cylinder, said ring having normal tolerances with said groove and cylinder wall such that said ring tends to pump oil to the top of said piston during reciprocation of said piston, a resilient packing ring seated in said groove behind said ring and expansible outwardly against said ring, passage means for delivering the said pressure within said cylinder to said piston ring so as to expand the packing ring against the piston ring, and means for preventing flow from beneath said ring and through said groove and passage means.

9. The structure of claim 8 wherein said packing ring 11 i is generally U shaped with one leg of said ring in engagement' with said piston rings, and said pressure delivery means communicates with the space within said packing ring. Y

10. The structure of claim 8 wherein said packing ring is a spirally wound tube in the space behind said piston rings, and the opposed ends of said tube communicate with the pressurized space of said cylinder.

11. The structure of claim 3 wherein said packing ring consists of a single tube, and said pressure delivery means communicates with said tube.

12. The structure of claim 3 wherein said packing ring a is generally U shaped in form with one leg shorter than the other and positioned against said piston rings, the

- bight portion of said ring having an inverted V shaped formwith the apex thereof opposed to said pressure.

.13. The structure of claim 8 wherein said packing ring has a generally U shaped form with one leg shorter thanthe other, the portion of the piston between said piston ng and said pressurized space having a smaller diameter than the remainder of the piston, said piston having a plurality of pressure passages spaced circumferentially thereof and communicating with the space between the legs of said packing ring and the space between .the cylinder wall and smaller wall portion of said piston.

References Cited by the Examiner UNITED STATES PATENTS 5/88 Davis 277-157 XR 11/09 Maples; 277-163 3/28 Werner c 74-589 10/38 Wenzel 277-58 XR 10/40 OLeary 74-589 7/41 Vickers 184-6 6/44 Buchet 74-592 XR 3/49 Patterson 184-18 12/51 Hornbostel 277-34 XR 5/55 Patterson 277-165 5/56 Delahay 184-18 XR 5/56 DErrico 277-165 6/56 Kriiger "I 309-48 12/56 Patterson 184-18 1/59 Parks et al. 267-1 4/60 Patterson 18-18 9/62 Mansoff 184-6 FOREIGN PATENTS 11/54 France.

3/ 19. Germany. 12/54 Germany.

LAVERNE D. GEIGER, Primary Examiner. 'BaoUoH o DURHAM, EMILEPAUL,

Examiners. 

1. THE METHOD OF LUBRICATING AND SEALING A PRESSURIZED CYLINDER AND PISTON COUNTERBALANCE ASSEMBLY IN WHICH A SEALING, FIRST POOL OF LUBRICANT IS MAINTAINED BETWEEN THE PRESSURIZED CYLINDER SPACE AND THE SIDE OF THE PISTON OPPOSED THERETO, AND IN WHICH A PORTION OF THE PISTON MAY MOVE INTO A SECOND POOL OF LUBRICANT AT A LOWER PORTION OF THE CYLINDER FOR LUBRICATION OF THE OPPOSED PISTON AND CYLINDER WALLS, INCLUDING THE STEPS OF UTILIZING THE NORMAL PUMPING ACTION OF THE PISTON TO MOVE LUBRICANT ALONG SAID OPPOSED WALLS FROM SAID SECOND POOL TO SAID FIRST POOL, AND REMOVING LUBRICANT FROM SAID SECOND POOL AND DELIVERING SAME TO SAID FIRST POOL INDEPENDENTLY OF SAID PUMPING ACTION WHEN THE LEVEL OF LUBRICANT IN SAID SECOND POOL INCREASES BEYOND A PREDETERMINED LEVEL. 